<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body{
            text-align: center;
        }
        div{
            margin-top: 20px;
            margin-left: 480px;
        }
        #box{
            width: 500px;
            height: 100px;
            border: 2px solid rosybrown;
        }
    </style>
</head>
<body>
    <input type="text" id="input">&nbsp;
    <button onclick="start()">复制</button>
    <div id="box">  

    </div>
    <script>
        var inputText = document.getElementById('input');
        function start(){
            document.getElementById('box').innerText = inputText.value;  
        }
    </script>
</body>
</html>